Wood joints

Summary: Learn the different types of wood joints and the different ways to join wood, learn how to join wood, mitre joints, butt joints, mortise and tenon joints, scarf joints, dovetail joints and halving Joints.

Butt joints

Butt joints are the simplest and weakest form of joint where one section of wood is butted head-on to another.

The joint can be nailed, glued, or screwed, or end to edge joints can be joined with corrugated or u-shaped fasteners.

If the joint is fixed with dowels inserted into mortises it is known as a dowel joint.

Where sections of wood are butted in a corner, you may need to fit a joining strip.

Biscuit butt joints are reinforced with an oval piece of wood fitted in matching mortises in both members of the joint. The biscuit absorbs some moisture from the glue and swells up in the mortise, creating a tightly fitting joint.

Knock-down fasteners are typically used for flat-pack furniture. Male and female parts are attached to the members and joined with a lock or screw. This is sometimes called a knock down joint.

Mitre joints

Mitring is a useful technique for joining sections of wood as it makes a neater joint than a straight butt joint. It is particularly useful when it comes to running skirting boards, dados, or worktops around a corner.

To measure a mitre angle, calculate half the angle of the corner. Most walls join at a 90º right-angle and will therefore require members to be cut at 45º angles.

If corners are not square, an angle finder would comes in useful for working out the angle.

The easiest way to make a mitre cut is to use a power mitre saw. This will save you the trouble of measuring and marking angles on the wood, and make a neater cut. Simply clamp the wood to the saw and set the blade to the desired angle.

Mortise and tenon joints

One member has a recess or cavity cut into it, which interlocks with a matching peg on the other member to form a joint, as used in a mortise lock on doors. The part with the hole is called the mortise, and the male part the tenon. Fixed with glue, pins or simply wedged.

Scarf joints

A stronger joint than a butt joint, a scarf joint is often used when the materials being joined are not long enough or when an invisible glue line is required. To form the joint, cut both members to a fine tapered point, using an angle of between 1:8 and 1:10.

Dovetail joints

Formation: A series of pins cut into one half of the joint interlock with a series of recesses cut into the other half.

Dovetail joints are used where a strong joint is needed such as for a drawer.

A sliding dovetail is used to join members at right angles – one member slides into a groove cut in the other.

Similar to a combing joint except that the pins are not square but slightly angled.

Halving Joints

A halving joint is simply where one piece of wood crosses over another. Half the thickness of the timber is removed from each piece so that they interlock to form a flush joint. There are various ways of interlocking the sections:

A cross halving joint simply involves rebates cut in both members being joined so that they interlock in the middle of the cross.

A Tee halving joint is formed by rebating the top of one member and the middle of the other

A corner halving joint involves rebating the ends of both members so that they interlock in the corner.

A dovetail halving joint involves cutting the sides of both members at an angle of about 30 degrees so that the interlocking pieces resemble a tapered dove’s tail.